Damper assembly

ABSTRACT

A damper assembly includes an outer cylinder, an inner cylinder positioned at least partially within the outer cylinder, a cap coupled to the inner cylinder, and a plunger positioned radially inward from the inner cylinder and coupled to a rod. The plunger, the cap, and an interior of the inner cylinder at least partially define a first chamber. The suspension system further includes a passage extending through the rod and fluidly coupled with the first chamber, a piston coupled to the inner cylinder and extending radially outward toward the outer cylinder, a first port in fluid communication with the plunger through the passage, and a second port in fluid communication with the piston. The piston, an exterior surface of the inner cylinder, and the outer cylinder at least partially define a second chamber.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/517,209, filed Jul. 19, 2019, which is a continuation of U.S.application Ser. No. 15/707,675, filed Sep. 18, 2017, now U.S. Pat. No.10,422,403, which is a continuation of U.S. application Ser. No.14/846,600, filed Sep. 4, 2015, now U.S. Pat. No. 9,765,841, which is acontinuation of U.S. application Ser. No. 13/047,648, filed Mar. 14,2011, now U.S. Pat. No. 9,127,738, all of which are incorporated hereinby reference in their entireties.

BACKGROUND

The present application relates general to the field of suspensionsystems for vehicles. More specifically the present application relatesto hydraulic shock absorbers.

Dashpots, and more specifically dampers, function as shock absorbers forvehicles. The dampers are typically formed from hydraulic cylinders,such as double-acting cylinders. The hydraulic cylinder includes a rodend, a cap end, and a plunger (or piston) on an end of a rod. Movementof the plunger drives hydraulic fluid into and out of the rod and capends. Friction from movement of the hydraulic fluid through the cylinderand associated plumbing dissipates energy associated with actuation ofthe suspension system in a manner proportional to the velocity of theactuation.

SUMMARY

One exemplary embodiment relates to a damper assembly including an outercylinder, an inner cylinder positioned at least partially within theouter cylinder, a cap coupled to the inner cylinder, and a plungerpositioned radially inward from the inner cylinder and coupled to a rod.The plunger, the cap, and an interior of the inner cylinder at leastpartially define a first chamber. The suspension system further includesa passage extending through the rod and fluidly coupled with the firstchamber, a piston coupled to the inner cylinder and extending radiallyoutward toward the outer cylinder, a first port in fluid communicationwith the plunger through the passage, and a second port in fluidcommunication with the piston. The piston, an exterior surface of theinner cylinder, and the outer cylinder at least partially define asecond chamber.

Another exemplary embodiment relates to a damper assembly including anouter cylinder, an inner cylinder positioned at least partially withinthe outer cylinder, a cap coupled to the inner cylinder, a plungerengaging an interior of the inner cylinder and coupled to a rod, whereinthe plunger, the cap, and the interior of the inner cylinder at leastpartially define a first chamber, a passage extending through the rodand fluidly coupled with the first chamber, and a piston coupled to theinner cylinder and extending radially outward toward the outer cylinder.The piston, an exterior surface of the inner cylinder, and the outercylinder at least partially define a second chamber. The plungerprevents fluid from exiting the first chamber between the inner cylinderand the rod.

Still another exemplary embodiment relates to a vehicle including avehicle body, a series of wheel end assemblies, and a suspension systemcoupling the wheel end assemblies to the vehicle body. The suspensionsystem includes a first damper and a second damper. The first damperincludes a first chamber at least partially defined by a first movablesurface of a plunger and by an inner cylinder, the plunger being movablerelative to and within the inner cylinder to adjust a volume of thefirst chamber, and a second chamber at least partially defined by asecond movable surface of a piston and by an outer cylinder, the secondchamber being fluidly separate from the first chamber. The pistonextends outwardly away from the inner cylinder toward the outercylinder. The second damper includes a third chamber having a variablevolume and a fourth chamber having a variable volume. The first chamberis fluidly coupled to the third chamber, and the second chamber isfluidly coupled to the fourth chamber.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, in which:

FIG. 1 is a perspective view of an axle assembly according to anexemplary embodiment of the invention.

FIG. 2 is a perspective view of a suspension system of the axle assemblyof FIG. 1.

FIG. 3 is a sectional view of a damper according to an exemplaryembodiment of the invention.

FIG. 4 is a sectional view of the damper of FIG. 3, taken along line 4-4as shown in FIG. 3.

FIG. 5 is a sectional view of a damper according to another exemplaryembodiment of the invention.

FIG. 6 is a sectional view of the damper of FIG. 5, in anotherconfiguration.

FIG. 7 is a sectional view of a damper according to yet anotherexemplary embodiment of the invention.

FIG. 8 is a sectional view of a damper according to still anotherexemplary embodiment of the invention.

FIG. 9 is a perspective view of dampers of the axle assembly of FIG. 1.

FIG. 10 is a schematic diagram of a vehicle suspension system and adamper according to another exemplary embodiment of the invention.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for the purpose of description onlyand should not be regarded as limiting.

Referring to FIG. 1, an axle assembly 110 is configured for use with avehicle. The vehicle may be a military vehicle, a utility vehicle suchas a fire truck, a tractor, construction equipment, a sport utilityvehicle, or another type of vehicle. According to an exemplaryembodiment, the axle assembly 110 includes a differential 112 connectedto half shafts 114, which are each connected to a wheel end assembly116. The wheel end assembly 116 may include brakes, a gear reduction,steering components, a wheel hub, a wheel, and other features. Thedifferential 112 is further configured to be connected with a driveshaft of the vehicle, receiving rotational energy from a prime mover ofthe vehicle, such as a diesel engine. The differential 112 thenallocates torque provided by the prime mover between the half shafts 114of the axle assembly 110. The half shafts 114 deliver the rotationalenergy to each wheel-end assembly 116.

Movement of the wheel end assembly 116 is at least partially controlledby a suspension system 118. The suspension system 118 includes a spring120, a damper 122, an upper support arm 124, and a lower support arm126. The upper and lower support arms 124, 126 couple the wheel endassembly 116 to the vehicle body, such as to a chassis, a side plate, ahull, or another part of the vehicle body. According to an exemplaryembodiment, the vehicle may be configured for operation on both pavedand rough, off-road terrain. As the vehicle travels over uneven terrain,the upper and lower support arms 124, 126 guide the vertical movement ofthe wheel end assembly 116 and a stopper 128 provides an upper bound.

Referring to FIG. 2, according to an exemplary embodiment the suspensionsystem 118 includes one or more high-pressure gas or hydraulic fluidcomponents. In some embodiments, the spring 120 is a high-pressure gasspring 120. In such embodiments, the suspension system 118 furtherincludes at least one high-pressure gas pump 130, such as a separatehigh-pressure gas pumps 130 associated with each spring 120. Inpreferred embodiments, the gas of the pump 130 and spring 120 is atleast 90% formed from an inert gas, such as nitrogen, argon, helium,etc., which may be stored, provided, or received in one or morereservoirs (e.g., central reservoir, tank). During operation, the pump130 selectively provides gas, under pressure, to the high-pressure gasspring 120 and/or to reservoirs, tanks, accumulators, or other devices.In some embodiments, additional fluid (e.g., gas, hydraulic fluid) maybe pumped to the springs 120 and/or the dampers 122 to change the rideheight of the vehicle by lifting or lowering the body of the vehiclewith respect to the ground.

Referring now to FIGS. 3-4, a damper assembly 210 (e.g., damper) may beused with a suspension system (see, e.g., suspension system 118 of FIGS.1-2), and includes an outer cylinder 212 and an inner cylinder 214. Theinner cylinder 214 is at least partially positioned within the outercylinder 212. According to an exemplary embodiment, a cap 216 (FIG. 3)closes (e.g., seals, caps) one end of each of the inner and outercylinders 214, 212. The inner cylinder 214 is received within a plunger218 that moves relative to the inner cylinder 214. As such, a firstchamber 220 is at least partially defined by the plunger 218, the cap216, and an interior of the inner cylinder 214. Movement of the plunger218 relative to the inner cylinder 214 changes the volume of the firstchamber 220.

According to an exemplary embodiment, the damper assembly 210 furtherincludes an annular piston 222, which moves relative to the outercylinder 212. The annular piston 222 is round and includes a ring-shapedcross-section. At least a portion of the annular piston 222 transverselyextends between the inner and outer cylinders 214, 212. A barrier 224,such as a rod-end head or rod gland, also transversely extends betweenthe inner and outer cylinders 214, 212. A second chamber 226 is at leastpartially defined by the barrier 224, the annular piston 222, anexterior surface of the inner cylinder 214, and the outer cylinder 212.The second chamber 226 is an annular chamber, and may include one ormore sub-chambers divided by structural partitions, but in fluidcommunication with one another (see generally second chamber 428 asshown in FIG. 7).

According to an exemplary embodiment, the damper assembly 210 furtherincludes a first aperture 228 (e.g., opening, hole, conduit) associatedwith the first chamber 220 and a second aperture 230 associated with thesecond chamber 226. In some embodiments, the first aperture 228 isformed in the cap 216 and is connected to external transfer tubes orpipes (see generally hydraulic lines 132 as shown in FIGS. 1-2). Thefirst aperture 228 allows fluid (e.g., hydraulic fluid, oil, gas, etc.)to flow into and out of the first chamber 220.

In some embodiments, the second aperture 230 is formed in the barrier224 and is connected to external transfer tubes or pipes. The secondaperture 230 allows fluid to flow into and out of the second chamber226. Either or both of the first and second apertures 228, 230 mayinclude valves (e.g., directional-control valves; see, generally modularvalve assembly 624, 626 as shown in FIG. 9). In other contemplatedembodiments, the damper assembly 210 functions as a spring or anaccumulator, and the first or the second chamber 220, 226 may notinclude an aperture.

Still referring to FIGS. 3-4, the annular piston 222 is fixed to theplunger 218. As the plunger 218 moves forward, pushing fluid out of thefirst chamber 220, the annular piston 222 also moves forward at the samerate, pulling fluid into the second chamber 226. In other embodiments,the annular piston 222 is fixed to the inner cylinder 214, which maymove relative to both the plunger 218 and to the outer cylinder 212 (seegenerally annular piston 324 and inner cylinder 314 as shown in FIG. 5).

According to an exemplary embodiment, the portion of the plunger 218 atleast partially defining the first chamber 220 has a cross-sectionalarea that is substantially equal to that of the portion of the annularpiston 222 at least partially defining the second chamber 226 (e.g.,one-to-one working area ratio). As such, the rate of volume changewithin the first chamber 220, as the plunger 218 moves, matches the rateof volume change within the second chamber 226 as the annular piston 222moves. Correspondingly, in such an embodiment the rate of hydraulicfluid out of one chamber 220, 226 matches the rate of hydraulic fluidentering the other chamber 226, 220.

In a configuration in which the damper assembly 210 is usedindependently, not cross-linked with another damper, the first aperture228 may be coupled to the second aperture 230. Hydraulic fluid from oneof the first and second chambers 220, 226 may flow directly to the otherof the first and second chambers 220, 226 without use of an intermediateaccumulator or reservoir, and without using a double-rod end cylinderconfiguration. No make-up volume of hydraulic fluid is required.

In another embodiment, a third chamber 232 is at least partially definedby the cap 216, the interior of the outer cylinder 212, the exterior ofthe inner cylinder 214 and the annular piston 222. As shown in FIG. 4,the side of the annular piston 222 that is at least partially definingthe third chamber 232 has about a twenty-five percent larger workingarea than the side of the annular piston 222 that is defining the secondchamber 226. In contemplated embodiments, the second and third chambers226, 232 may contain hydraulic fluid, with the first chamber 220 forminga vacuum, containing inert gas, or in communication with ambient air. Insuch embodiments, the extend-to-retract area ratio is about 1-to-1.25(e.g., near equal area). In designs where the outer diameter of theinner cylinder 214 and the inner diameter of the outer cylinder 212increase, the extend-to-retract area may more closely approximate a1-to-1 ratio.

Referring to FIGS. 5-6 a damper assembly 310, as may be used with thesuspension system 118 of FIGS. 1-2, includes an outer cylinder 312 andan inner cylinder 314. The inner cylinder 314 is positioned at leastpartially within the outer cylinder 312 and a plunger 316 is received inthe inner cylinder 314. A cap 318 closes the end of the inner cylinder314 on a side of the inner cylinder 314 that is opposite to the plunger316, such that a first chamber 320 is at least partially defined by theface of the plunger 316, the cap 318, and the interior of the innercylinder 314. Movement (e.g., translation) of the plunger 316 relativeto the inner cylinder 314 changes the volume of the first chamber 320.According to an exemplary embodiment, a rod 322 is fixed to the plunger316 and extends at least partially within the inner cylinder 314. Insome such embodiments, the rod 322 is fixed to the outer cylinder 312.

The damper assembly 310 further includes an annular piston 324 fixed tothe inner cylinder 314 on an end of the inner cylinder 314 opposite tothe cap 318. As such, during operation of the damper assembly 310, theannular piston 324 moves with the inner cylinder 314 relative to boththe outer cylinder 312 and the rod 322. The annular piston 324 and abarrier 326 transversely extend between the inner and outer cylinders314, 312, and a second chamber 328 is at least partially defined by thebarrier 326, the annular piston 324, the exterior of the inner cylinder314, and the interior of the outer cylinder 312. According to anexemplary embodiment, the plunger 316 has a cross-sectional area that issubstantially equal to the cross-sectional area of the portion of theannular piston 324 that is at least partially defining the secondchamber 328 (i.e., one-to-one working area ratio).

The damper assembly 310 includes a first aperture 330 (e.g., conduit,tunnel, passage) coupling the first chamber 320 to a first port 332located on the exterior of the damper assembly 310, and a secondaperture 334 coupling the second chamber 328 to a second port 336 alsolocated on the exterior of the damper assembly 310. According to anexemplary embodiment, the first and second ports 332, 336 are proximateto one another, allowing for coupling of a modular valve assembly 338(FIG. 6) or another attachment to the damper assembly 310 that maysimultaneously access the first and second chambers 320, 328 via thefirst and second ports 332, 336.

According to an exemplary embodiment, the first aperture 330 extendsfrom the first port 332 through the rod 322 and the plunger 316 to thefirst chamber 320. The second aperture 334 extends from the second port336, through the interior to the outer cylinder 312 to the secondchamber 328. In some embodiments, the second aperture 334 extends alongan outside portion of the second chamber 328, while in otherembodiments, the second aperture 334 extends along an inside portion ofthe second chamber 328, such as being integrated with the rod 322 (see,e.g., aperture 440 as shown in FIG. 7).

During operation of the damping assembly 310, fluid flows into the firstport 332, through the first aperture 330 in the rod 322 and the plunger316, and into the first chamber 320. The inner cylinder 314 slides awayfrom the plunger 316, and the volume of the first chamber 320 increases.Simultaneously the annular piston 324 slides toward the barrier 326,decreasing the volume of the second chamber 328. Fluid flows from thesecond chamber 328, through the second aperture 334 and to the secondport 336. Compare the damper assembly 310 in a retracted configurationas shown in FIG. 5 with the damper assembly 310 in an extendedconfiguration as shown in FIG. 6. When the damper assembly 310 is usedindependently and not cross-linked with another damper, the firstaperture 330 may be coupled to the second aperture 334, and hydraulicfluid from one of the first and second chambers 320, 328 may flowdirectly to the other of the first and second chambers 320, 328.

Referring now to FIG. 7, a damper assembly 410, according to anotherembodiment, includes an outer cylinder 412, an inner cylinder 414 havinga cap 416, and a plunger 418 received in the inner cylinder 414. A firstchamber 442 is at least partially defined by the inner cylinder 414, thecap 416, and the face of the plunger 418. An annular piston 420 is fixedto the inner cylinder 414 on an end of the inner cylinder 414 oppositeto the cap 416. A first part 422 of the annular piston 420 and a barrier424 both transversely extend between the inner and outer cylinders 414,412. A first portion 426 (e.g., sub-chamber) of a second chamber 428 isat least partially defined by the barrier 424, the first part 422 of theannular piston 420, the exterior of the inner cylinder 414, and theinterior of the outer cylinder 412.

The damper assembly 410 of FIG. 7 further includes a second part 430 ofthe annular piston 420, which transversely extends between the innercylinder 414 and a rod 432 fixed to the plunger 418. As such, the secondchamber 428 includes a second portion 434 that is at least partiallydefined by the rod 432, the second part 430 of the annular piston 420,the interior of the inner cylinder 414, and the rear of the plunger 418.The first and second portions 426, 434 of the second chamber 428 are influid communication with one another such that hydraulic fluid from oneof the portions 426, 434 may flow to the other, and vice versa, throughan opening 436. According to an exemplary embodiment, the face ofplunger 418 has a cross-sectional area that is substantially equal tothe net cross-sectional area of the parts 422, 430 of the annular piston420 that are at least partially defining the first and second portions426, 434 of the second chamber 428.

Apertures 438, 440 are formed in the damper assembly 410 correspondingto each of the chambers 428, 442. The aperture 438 associated with thefirst chamber 442 extends through the rod 432 and connects the firstchamber 442 with a first port 444. The aperture 440 associated with thesecond chamber 428 extends through the rod 432 and connects the secondchamber 428 with a second port 446. The first and second ports 444, 446are on opposite sides of the damper assembly 410.

Referring now to FIG. 8, a damper assembly 510 is designed forposition-dependent damping. The damper assembly 510 includes a firstport 512, which may be connected to external compression valving (see,e.g., modular valve assembly 338 as shown in FIG. 6). A first aperture514 connects the first port 512 to a first chamber 516 (e.g., extensionflow collection volume). A deflected disc check valve 518 is positionedbetween the first aperture 514 and the first chamber 516, allowing flowinto the first chamber 516 and preventing flow out of the first chamber516.

A plunger 520 at least partially defines the first chamber 516, whichincludes primary flow openings 524 and a series of auxiliary openings522 for changing the damping response as a function of the number of theauxiliary openings 522 in operation. More auxiliary openings 522 inoperation provide lesser resistance to the flow. The operability of theauxiliary openings 522 depends upon the relative configuration of theplunger 520 within the first chamber 516, which corresponds with thedegree to which the damper assembly 510 is extended.

The damper assembly 510 further includes a second port 524, which may beconnected to external recoil valving. A second aperture 526 connects thesecond port 524 to a second chamber 528 (e.g., recoil flow collectionvolume) of the damper assembly 510. According to an exemplaryembodiment, an annular piston 530 is associated with the second chamber528. The second chamber 528 also includes one or more position-dependentrecoil flow ports 532.

Similar to the damper assemblies 210, 310, and 410, the damper assembly510 includes an inner cylinder 534 and an outer cylinder 536. However,only a portion of the inner cylinder 534 (e.g., less than half) extendswithin the outer cylinder 536. Also, a rod 538 of the damper assembly510 is hollow and includes an empty volume 540. In contemplatedembodiments, the empty volume 540 may be used to support a gas spring(see, e.g., spring 120 as shown in FIG. 1) or a portion thereof,integrating the gas spring with the hydraulic damper 510.

Referring to FIG. 9, a damper set 610 (e.g., system), configured for usewith the axle assembly 110, includes at least two dampers, such as afirst damper 612 and a second damper 614. According to an exemplaryembodiment, each damper 612, 614 includes two chambers 616, 618, 620,622, such as rod-end chambers 616, 620 and cap-end chambers 618, 622(see, e.g., chambers 320, 328 as shown in FIG. 5). Each chamber 616,618, 620, 622 includes a surface or wall that moves to change the volumeof the chamber, such as a piston or plunger (see, generally plunger 316and annular piston 324 as shown in FIG. 5). Within each damper 612, 614the movable surfaces of the two chambers 616, 618 and 620, 622 may beformed on opposite sides of the same element (e.g., a piston), or may besurfaces of separate elements (e.g., two different pistons). Accordingto an exemplary embodiment, the movable surfaces of each of the chambers616, 618, 620, 622 in the damper set 610 have substantially the samecross-sectional area (e.g., working area).

According to an exemplary embodiment, the damper set includes a modularvalve assembly 624, 626 fastened to each damper 612, 614. The modularvalve assemblies 624, 626 include valves (e.g., passive valving, pistonvalve, deflected disc blow-off valve acting on the rebound side) thatcontrol fluid flow to and from the chambers 616, 618 and 620, 622 ofassociated dampers 612, 614. In contemplated embodiments, the modularvalve assemblies 624, 626 may be controlled by a computerized controllerand may be configured to operate the damper set 610 in different modesdepending upon loading of the associated vehicle (e.g., controllingdamping stiffness and response as a function of axle load and/orterrain). In some embodiments, the modular valve assemblies 624, 626 aredesigned to be easily switchable with other modular valve assembliesincluding different strength valves, depending upon axle load or otherfactors. According to an exemplary embodiment, the modular valveassemblies 624, 626 are bolted to the dampers 612, 614, such as overports associated with the chambers 616, 618, 620, 622 of the dampers612, 614 (see, e.g., ports 332, 336 as shown in FIGS. 5-6).

According to an exemplary embodiment, the dampers 612, 614 of the damperset 610 are cross-plumbed (e.g., cross-linked). Hydraulic lines 628, 630connect opposite chambers 618, 620 and 616, 622 of different dampers612, 614, such as connecting a rod-end of one damper with a cap-end ofanother damper on an opposite side of the axle assembly 110. The dampers612, 614 may be cross-plumbed in a “walking beam” configuration for atandem axle, and/or between dampers 122 on separate axle assemblies ofthe vehicle (e.g., between dampers located front-to-back, or diagonallylocated with respect to each other, etc.). In some such embodiments, thehydraulic lines 628, 630 are coupled to the dampers 612, 614 by way ofthe modular valve assemblies 624, 626.

In some embodiments, each hydraulic line 628, 630 includes an associatedaccumulator 632, 634. The accumulators 632, 634 may be fastened to thedampers 612, 614, or may be located elsewhere in the axle assembly 110.According to an exemplary embodiment, the accumulators 632, 634 may beused with the modular valve assemblies 624, 626 to operate the damperset 610 in different modes, depending upon loading, terrain, speed, etc.of the associated vehicle.

According to an exemplary application, as the vehicle turns, the damper612 on the inside of the turn retracts. Retraction of the damper 612increases pressure in the cap-end chamber 618 and decreases pressure inthe rod-end chamber 616 of the damper 612. Concurrently, the damper 614on the outside of the turn receives and supplies the hydraulic fluid ofthe damper 612. Hydraulic fluid is transferred from the cap-end chamber618 of the damper 612 to the rod-end chamber 620 of the damper 614, andfrom the cap-end chamber 622 of the damper 614 to the rod-end chamber616 of the damper 612.

In general, without use of a double-rod cylinder providing equal areasto both sides of a plunger, pressure applied by the cap end of aconventional hydraulic damper is greater than the pressure applied bythe rod end, which may raise or lower the chassis of the vehicle goingaround a turn. Use of a double rod-end cylinder may help prevent vehiclelifting, but the double rod-end cylinder typically requires a largertravel than a single rod-end cylinder, and may not be compatible with acompact suspension. However, because the moveable surfaces of each ofthe chambers 616, 618, 620, 622 in the damper set 610 have substantiallythe same cross-sectional area, the pressure applied by the cap-endchamber 618 of the damper 612 is oppositely applied to the rod-endchamber 620 of the damper 614. Equal and opposite pressures are intendedto improve the ride quality of the associated vehicle by preventinglifting of the vehicle as the vehicle turns, such as raising andlowering of the chassis by unequal pressures loading the dampers 612,614.

In contemplated embodiments, the cap-end chambers 618, 622 and therod-end chambers 616, 620 of the dampers 612, 614 may be coupled via thehydraulic lines 628, 630. In still other embodiments, the modular valveassemblies 624, 626 allow for switching of the chambers 616, 618, 620,622 that are respectively coupled, such as from cap-end chamber 618 androd-end chamber 620 to cap-end chamber 618 and cap-end chamber 622. Theswitching may be directed via the computerized controller, which may bemanually controlled from the cabin of the associated vehicle by anoperator and/or automatically controlled by the computerized controlleras a function of location, speed, vehicle tilt, etc.

Referring now to FIG. 10, a damper assembly 710 is designed for use witha rotary actuator 712 (e.g., steering gear). The damper assembly 710includes two chambers 714, 716 on opposing sides of a piston 718. Thepiston 718 is coupled to the rotary actuator 712 via a rack-and-piniongear arrangement 720. As such, the damper assembly 710 dissipates rotaryenergy and provides equal pressure for hydraulic fluid on both sides ofthe piston 718. In a configuration in which the damper assembly 710 isused independently, the first chamber 714 may be coupled to the secondchamber 716, and hydraulic fluid from one of the first and secondchambers 714, 716 may flow directly to the other of the first and secondchambers 714, 716, without use of an intermediate accumulator orreservoir (i.e., no make-up volume required).

The dampers 210, 310, 410, 510, and 710 are each configured to operatein a damper set, such as the damper set 610, which may be part of anaxle assembly for a vehicle, such as the axle assembly 110.Additionally, the dampers 210, 310, 410, 510, and 710 are configured tooperate in other applications, such as with landing gears of airplanes,suspension systems of railroad cars, and other industrial machinery.Further, the innovations described herein may be used with dampers anddamping systems associated with large structures, such as buildings andbridges, to dissipate energy of an earthquake, wind, rough seas, etc.

The construction and arrangements of the damper assembly, as shown inthe various exemplary embodiments, are illustrative only. Although onlya few embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process, logicalalgorithm, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present invention.

1. A damper assembly comprising: an outer cylinder; an inner cylinder positioned at least partially within the outer cylinder; a cap coupled to the inner cylinder; a plunger positioned radially inward from the inner cylinder and coupled to a rod, wherein the plunger, the cap, and an interior of the inner cylinder at least partially define a first chamber; a passage extending through the rod and fluidly coupled with the first chamber; a piston coupled to the inner cylinder and extending radially outward toward the outer cylinder, wherein the piston, an exterior surface of the inner cylinder, and the outer cylinder at least partially define a second chamber; a first port in fluid communication with the plunger through the passage; and a second port in fluid communication with the piston.
 2. The damper assembly of claim 1, wherein the second port is in fluid communication with the piston through an aperture defined by a wall of the outer cylinder.
 3. The damper assembly of claim 1, wherein the plunger is configured to move relative to the inner cylinder, and wherein the piston is configured to move relative to the outer cylinder.
 4. The damper assembly of claim 3, wherein the plunger is fixed to an end of the rod, and wherein movement of the plunger relative to the inner cylinder changes a volume of the first chamber.
 5. The damper assembly of claim 4, wherein the movement of the plunger relative to the inner cylinder moves the piston relative to the outer cylinder and changes a volume of the second chamber.
 6. The damper assembly of claim 5, wherein when the volume of the first chamber increases, the volume of the second chamber decreases.
 7. The damper assembly of claim 1, further comprising a barrier extending between the inner cylinder and the outer cylinder, wherein the barrier at least partially defines the second chamber.
 8. The damper assembly of claim 7, further comprising an accumulator in fluid communication with at least one of the first chamber and the second chamber.
 9. The damper assembly of claim 8, wherein the first chamber is at least partially defined by a face of the plunger, and wherein the face of the plunger has a cross-sectional area that is substantially equal to the cross-sectional area of a portion of the piston that at least partially defines the second chamber.
 10. The damper assembly of claim 1, wherein the cap is threadably coupled to the inner cylinder.
 11. The damper assembly of claim 10, wherein the inner cylinder includes internal threads and a stem of the cap includes external threads adjustably received within the internal threads.
 12. The damper assembly of claim 1, wherein each of the first chamber and the second chamber receive hydraulic fluid.
 13. The damper assembly of claim 1, wherein the rod has an outer diameter that is smaller than an inner diameter of the inner cylinder.
 14. A damper assembly comprising: an outer cylinder; an inner cylinder positioned at least partially within the outer cylinder; a cap coupled to the inner cylinder; a plunger engaging an interior of the inner cylinder and coupled to a rod, wherein the plunger, the cap, and the interior of the inner cylinder at least partially define a first chamber, and wherein the plunger prevents fluid from exiting the first chamber between the inner cylinder and the rod; a passage extending through the rod and fluidly coupled with the first chamber; and a piston coupled to the inner cylinder and extending radially outward toward the outer cylinder, and wherein the piston, an exterior surface of the inner cylinder, and the outer cylinder at least partially define a second chamber.
 15. The damper assembly of claim 14, wherein relative displacement between the inner cylinder and the outer cylinder in a first direction increases a volume of the first chamber and decreases a volume of the second chamber.
 16. The damper assembly of claim 15, wherein relative displacement between the inner cylinder and the outer cylinder in a second direction opposite the first direction decreases the volume of the first chamber and increases the volume of the second chamber.
 17. The damper assembly of claim 14, wherein the plunger is fixed to an end of the rod, and wherein movement of the plunger relative to the inner cylinder changes a volume of the first chamber.
 18. The damper assembly of claim 17, further comprising a barrier extending between the inner cylinder and the outer cylinder, wherein the barrier at least partially defines the second chamber.
 19. A vehicle, comprising: a vehicle body; a plurality of wheel end assemblies; and a suspension system coupling the wheel end assemblies to the vehicle body, the suspension system comprising: a first damper comprising: a first chamber at least partially defined by a first movable surface of a plunger and by an inner cylinder, the plunger being movable relative to and within the inner cylinder to adjust a volume of the first chamber; and a second chamber at least partially defined by a second movable surface of a piston and by an outer cylinder, the second chamber being fluidly separate from the first chamber, wherein the piston extends outwardly away from the inner cylinder toward the outer cylinder; and a second damper comprising: a third chamber having a variable volume; and a fourth chamber having a variable volume, wherein the first chamber is fluidly coupled to the third chamber; and wherein the second chamber is fluidly coupled to the fourth chamber.
 20. The vehicle of claim 19, wherein the suspension system further comprises: a first accumulator coupled to a first conduit, the first conduit coupling the first chamber to the third chamber to facilitate fluid communication therebetween; and a second accumulator coupled to a second conduit, the second conduit coupling the second chamber to the fourth chamber to facilitate fluid communication therebetween, wherein a response of the first damper and the second damper is at least partially controlled via operation of the first accumulator and the second accumulator. 